There is compelling evidence for an autoimmune disease of the ovary. Ovarian autoimmunity may affect 1-2 million women in the US. In order to identify women with ovarian autoimmunity we developed prototype immunoassays to detect ovary specific autoantibodies, and used them to develop phenotypic information on the association of ovarian autoimmunity with premature menopause (premature ovarian failure or POF) and unexplained infertility. Further human research and clinical use depends on identification of the relevant protein antigens. The objective of the proposed study is to identify major autoantigens relevant to the phenotypes associated with ovarian autoimmunity. Previous studies suggest that ovary specific autoantibodies react with several ovarian antigens. In addition, autoimmune sera react with four predominant bands of ovarian protein in one-dimensional Western blots. This is consistent with other autoimmune diseases in which antibodies to multiple antigens have the most significant predictive value for disease. We will test the hypothesis that positive sera react with more than one major ovarian antigen (Aim 1). Proteomics methodology combined with the use of a systematically selected panel of autoimmune sera will be used to identify major protein antigens. Recombinant forms of the identified human proteins will be produced. The reaction of each identified protein with the autoimmune sera test panel will be evaluated to verify the authenticity of identified proteins. In Aim 2 the hypothesis that autoimmune POF and unexplained infertility share the same antigens will be tested in order to support the concept that they represent different stages of the same autoimmune disorder. The reaction of sera from women with POF and unexplained infertility will be compared by immunoassay using the identified proteins produced in Aim 1. Furthermore, previous studies showed that ovarian antibodies are associated with a low likelihood of pregnancy after infertility treatment. In Aim 3, the hypothesis that autoantibodies to identified proteins also predict a low likelihood of pregnancy in women with unexplained infertility after in-vitro fertilization will be tested. We will determine if autoantibodies to one antigen or a combination of antigens has predictive value for pregnancy. The proposed study is expected to improve the precision with which ovarian autoimmunity is detected. This will permit studies of disease pathogenesis, health risks associated with ovarian autoimmunity, genetic factors associated with disease susceptibility and improve clinical diagnosis. It will also contribute to a better understanding of an autoimmune disease that affects women's health.